• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1076-1079
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• 2001

This investigation reports the grinding characteristics of titanium alloy(Ti-6Al-4V). Grinding experiments were performed at various grinding conditions. The grinding forces and grinding force ratio were measured to investigate the grindability of titanium alloy with the Diamond and CBN wheel. To investigate the grinding characteristics of titanium alloy grinding force ratio and grinding ratio were measured. Surface profile of wheel was also measured with tracer and the ground surfaces and chip were observed with SEM. Grinding-ratio of titanium alloy was much lower than that of other materials. Grinding-ratio of titanium alloy with Diamond wheel was almost six times larger than that with CBN wheel.

• Journal of Welding and Joining
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• 제13권3호
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• pp.147-156
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• 1995

The change of microstructure in the bonded interlayer and tensile properties of joints were studied for liquid phase diffusion bonding using STS-310 and Incoloy-825 as base metal and base metal+B alloy as insert inetal. Main experimental results obtained in this study are as follows. 1) The optimum amount of B addition into the insert metal was found to be about 4mass%. 2) When isothermal solidification was completed, the microstructure in the bonded interlayer was the same with that of the base metal because of the grain boundary migration in the bonded interlayer. 3) All of the tensile specimen fractured at base metal and joints bonded at optimum condition exhibited tensile properties in excess of base metal requirements. 4) It was determined that fine car-borides and bordes such as M$_{23}$(C,B)$_{6}$, Cr$_{2}$B, and CrB in STS-310S and TiB in Incoloy-825 exist at the grain boundary around bonded interlayer. These precipitates almost disappeared after homogenizing treatment at 1373K for 86.4ks.s.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1252-1253
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• 2008

The $V_{1.8}W_{0.2}O_5$ thin films deposited on $Pt/Ti/SiO_2/Si$ substrates by RF sputtering method with different $Ar/O_2$ ratio. The $V_{1.8}W_{0.2}O_5$ thin films were measured electrical and structural properties, fairly good Temperature coefficient of resistance(TCR). It was found that electrical and structural properties, TCR properties of thin films were strongly dependent upon the $Ar/O_2$ ratio. The dielectric constant of the $V_{1.8}W_{0.2}O_5$ thin films with 50/20 ratio were 93 with a dielectric loss of 0.535, respectively. Also, the TCR values of the $V_{1.8}W_{0.2}O_5$ thin films with 50/20 ratio were -3.15%/$^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.394-397
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• 2001

In this paper, in-situ deposited $Ru/RuO_2$ bottom electrodes have been investigated as new bottom electrodes for PZT thin film capacitor application. As a comparison, structural and electrical properties of PZT thin films on Pt/Ti and $RuO_2$ bottom electrodes are also investigated. The use of $Ru/RuO_2$ hybrid electrodes showed better electrical properties in compression with $RuO_2$ bottom electrode. With increasing Ru electrode thickness, the PZT thin films showed preferred orientation along the (110) direction and and leakage current of PZT thin films were improved. The PZT thin films on Ru (100nm)/$RuO_2$ electrodes exhibited excellent ferroelectric properties such as remant polarization and coercive field of $7.2C/cm^2$ and 46.35 kV/cm, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.848-850
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• 1999

In this study, PZT etching was performed using planar inductively coupled Ar(20)/$Cl_2/BCl_3$ plasma, The etch rate of PZT film was 2450 $\AA/min$ at Ar(20)/$BCl_3$(80) gas mixing ratio and substrate temperature of $80^{\circ}C$. X-ray photoelectron spectroscopy (XPS) analysis for film composition was utilized. The chemical bond of PbO is broken by ion bombardment, and the peak of metal Pb in a Pb 4f peak begins to appear upon etching, decreasing Pb content faster than Zr and Ti. As increase content of additive $BCl_3$, the relative content of oxygen decreases rapidly. We thought that abundant Band BCl radicals made volatile oxy-compound such as $B_{x}O_{y}$ and/or $BClO_x$ bond. To understand etching mechanism, Langmuir probe and optical emission spectroscopy (OES) analysis were utilized for plasma diagnostic.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.125-126
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• 2006

The characteristics of the tool system give many effects into the costs and qualities for the finished components. Therefore, a tool life is one of the important issues on cold forging industry. However, since variables related with tool life are many complicated, the studies for solution should be investigated by the systematic research approach. In this study, heat-treatment of tool material is investigated to improve the tool life. Deep cryogenic treatment of tool steel is very efficient to improve the wear resistance due to the fine carbide. And, it is investigated that the shape and dimension of tool give effect into both tool life and quality of forged product.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.172-175
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• 2002

High speed machining is one of the most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when machining of micro groove in high speed machining a severely thermal damage was generated on workpiece and cutting tool. Generally, the cutting fluid is used to improve penetration. lubrication. and cooling effect. In order to rise the performance of lubrication. it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive. Therefore, the compressed chilly air with oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HrC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effect of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool lift of carbide tool coated TiAlN with compressed chilly air mist cooling was much longer than that of the dry and flood coolant when cutting the material.

• 천문학회보
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• 제41권1호
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• pp.77.2-77.2
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• 2016

We present preliminary results of the analysis of chemical abundances for seven hypervelocity star (HVS) candidates. These objects are G and K dwarfs in the Galactic disk selected from the Sloan Extension for Galactic Understanding and Exploration. Unlike other HVSs discovered thus far, their stellar orbits and kinematics suggest that they do not originate in the Galactic center or in an accretion event. These factors imply yet-unknown mechanisms that give rise to these kinematically-extreme disk stars. In order to study in detail their progenitors and possible formation mechanisms, we obtained spectra of these stars at a resolving power of R~6000, with the Dual Imaging Spectrograph at the Apache Point Observatory. We derive the abundances of chemical elements, C, Mg, Ca, Ti, Cr, Fe, and Ba from the observed spectra, using MOOG. We compare them with the ones of typical Galactic disk stars and discuss discrepancies between them to search for clues to their origin.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2501-2503
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• 1998

In this paper, the silicon-nitride membrane structure for IR sensor was fabricated through the etching and the direct bonding. The PTO layer as a IR detection layer was deposited on the membrane and its characteristics were measured. The attack of PTO layer during the etching of silicon wafer as well as the thermal isolation of the IR detection layer can be solved through the method of bonding/etching of silicon wafer. Because the PTO layer of c-axial orientation raised thermal polarization without polling, the more integration capability can be achieved. The surface roughness of the membrane was measured by AFM, the micro voids and the non-contacted area were inspected by IR detector, and the bonding interface was observed by SEM. The polarization characteristics and the dielectric characteristics of the PTO layer were measured, too.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.25-26
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• 2008

Electrical properties of Pt/Ti/Au/Pt contacts to n-GaAs were characterized as the V/III ratio of GaAs grown by metalorganic chemical vapor deposition were 25, 50, and 100, respectively. The samples have been annealed during 30sec at 350 and $450^{\circ}C$ in rapid thermal annealing, and those specific contact resistance investigated by using transmission line method. According to experimental results, the specific contact resistance between p-metal and GaAs was decreased as the V/III ratio was lower. These results indicate that Si doping concentration of GaAs increased as the vacancy of V-series of GaAs was high.